Aerodynamic ions generator is well known (see WO/2004/008597(A1) or IL/150766A) in which a high voltage terminal of high voltage AC power supply is via air capacitor and two different polarity diodes is coupled to ion ionizing electrodes.
Aerodynamic ions generator is well known (see WO/2004/008597(A1) or IL/150766A) in which a high voltage terminal of high voltage AC power supply is via air capacitor and two different polarity diodes is coupled to ion ionizing electrodes.
One of the limitations of the invention is the use of the motor shaft for connecting diodes mounted on the rotating part of the motor to the voltage terminal of the fixed AC high voltage generator.
In this case the mechanical contact causes friction and wear of the metal which in the long run reduces the continuous operation time of the device.
Another limitation is the low efficiency of energy transmission from the AC generator to ionizing electrodes which depends on the air capacitor capacitance.
Air capacitor capacitance is determined by the area of the stator and the rotor plates and the gap between them.
Because of very low dielectric constant of air (∈) big plate surface is required for energy transmission at a preset frequency of the AC generator, which makes the device bulky.
At the same time an increase of capacitance on the expense of reducing the gap between the plates is limited by a low breakdown voltage of the air of 3 kV/mm.
In practice, at reasonable sizes of the rotor and the stator plates and the gap between them the transmitted voltage does not exceed 5 kV, which prevents from yielding high ion emission currents.
Inventions are well-known in which air ionizing electrodes are implemented with a thin spring stretched with a spring (see for example U.S. Pat. No. 7,212,393.B2).
The limitation of such mechanical solution is that the tension of the wire remains constant during the ions generator operation and the out-of-service time.
Constant tension leads to the fatigue not only of the wire but also of the spring material; therefore taking into consideration the fatigue of materials with time, the tension force of the wire is preset to be higher than the required minimal value.
This leads to non-uniform wire thinning and consequently to non-uniform ions emission along its length.
Further, ion generators are well-known in which the ion emission as maintained constant through the control of the high voltage AC generator. The feedback control signal received from a sensor which is mounted at a certain distance from the air ionizing electrodes and responds to the ion emission level (see for example U.S. Pat. Nos. 4,740,862 and 6,850,403).
The limitation of these inventions is in a very high ions emission level.
This is due to the fact that the ions emission level required for the sensors operation is dozens of times higher than the ions level at the ions generator output.
The high level of the ions emission has two negative consequences:
firstly, the metal emission from the ionizing electrodes is increased, which is extremely undesirable when ion generators are used in the clean rooms of the semiconductors industry;
and secondly, the ozone (O3) level is increased, which is an undesirable byproduct of the ionization process.